Process for recovering hydrocarbon from subterranean strata



3,102,588 Patented Sept. 3, 1963 United States Patent ()fifice 3,102,588 PROiIESS FOR RECQVERKNG HYDROCARBON FROM SUBTERRANEAN STRATA U Henry B. Fisher, Bartiesviile, Girla, assignor to Phillips. Petroleum Company, a corporation of Delaware No Drawing. Filed July 24, 1959, Ser. No. 329,230 11 Qlaims. (6]. 166-11) This invention relates to a process for recovery of hydrocarbons from a carbonaceous stratum by hydrogenation, whereby the desired temperature conditions for hydrogenation are attained and maintained by an in situ combustion process as required.

In situ combustion in the recovery of hydrocarbons from underground strata containing carbonaceous material is becoming more prevalent in the petroleum industry. In this technique of production, combustion is initiated in the carbonaceous stratum and the resulting combustion zone is caused to move thru the stratum by either inverse or direct air drive whereby the heat of combustion of a substantial proportion of the hydrocarbon in the stratum drives out and usually upgrades a substantial proportion of the unburned hydrocarbon material.

The ignition of carbonaceous material in a stratum 2 more readily recoverable. l A further object is to provide a process for recovering hydrocarbons from a carbonaceous stratum containing solid, semi-solid, and highly viscous carbonaceous material which result in plugging 5 the stratum when produced by direct in situ combustion.

bons) Another object is to recover hydrocarbons from reservoirs too deep to pump with conventional pumping equipment. Other objects of the invention will become apparent to one skilled in the art upon consideration of the accompanying disclosure. p I

A broad aspect of the invention comprises heating a section of a carbonaceous stratum to a temperature subcombustion zone around the ignition Well is expanded by around a borehole therein followed by injection of air thru the ignition borehole and recovery of product hydrocarbons and combustion gas thru another borehole in the stratum is a direct air drive process for efiecting in situ combustion and recovery of hydrocarbons from the stratum. In this type of operation the stratum usually plugs in front of the combustion zone because a heavy viscous liquid bank of hydrocarbon collects in the stratum in advance of the combustion zone which prevents movement of air to the combustion process. To overcome this difliculty and to permit the continued progress of the combustion zone thru the stratum, inverse air injection has been resorted to. By this technique, a combustion zone is established around an ignition borehole by any suitable means and air is fed thru the stratum to the combustion zone from one or more surrounding boreholes.

In situ combustion techniques are being applied to tar sands, shale, Athabasca sand and other strata in virgin state, to coal vein-s by fracturing, and to strata partially depleted by primary and even secondary and tertiary recovery methods.

,When the in situ combustion process is applied in the recovery of hydrocarbons from carbonaceous strata containing semi-solid to solid hydrocarbons, a substantial portion of the hydrocarbon material driven from the stratum is of high viscosity and requires upgrading after recovery. This is also trueto a lesser extent when producing strata containing less viscous hydrocarbon material. After producing the usual type of oil smd by conventional primary and secondary recovery techniques, there remains in the sand a substantial amount of heavy semi-solid to solid residual carbonaceous material which would be valuable if recovered in upgraded form. This invention is concerned with a method or process for producing such strata containing semi-solid to solid and other highly viscous hydrocarbons so as to recover valuable upgraded hydrocarbons therefrom. it is also concerned with recovery of upgraded hydrocarbons from oil reservoirs containing oil of a wide range of viscosities.

Accordingly, it is an object of the invention to provide injecting combustion-supporting gas either thru the ignition Well or thru one or more oiiset Wells in the stratum so that the combustion-supporting gas passes into the combustion zone and burns additional hydrocarbon material, simultaneously moving the combustion zone into the stratum farther from the ignition well.

The combustion zone may be expanded around a central ignition well surrounded by a ring of oiiset wells or it may be established along a line of ill-line ignition Wells by igniting the stratum around alternate Wells and driving the resulting combustion zone to the adjacent ternate wells either by direct or inverse injection of air or other combustion-supporting gas. When injecting air inversely to the movement of a combustion front in a stratum, it is advantageous to incorporate therein fuel gas, such as propane or other normally gaseous hydrocarbon, in a concentration in the range of about 1 to 4 volume percent. This is absolutely essential when igniting a stratum by inverse injection of the gas thru offset Wells.

After establishing a combustion zone of substantial proportions, such as one extending several feet from the ignition well, and at a temperature of at least 1000 and preferably 1200 F the flow of air to the combustion zone is terminated and hydrogen is injected into the hot combustion zone so as to initiate hydrogenation of hydrocarbons in the hot zone. alone or in admixture with an inert gas such as combustion gas, CO or nitrogen which assists in flushing hydrocarbons from the stratum. Because of the exothermic nature of the hydrogenation reaction, itis feasible in some types of. formations to continue the injection of hydrogen indefinitely with maintenance of the required hydrogenation temperature in the reaction zone and fiuidization and flushing out of normally semi-solid to solid hydrocarbons,

a substantial proportion of which are hydrogenated to more volatile hydrocarbons.

To illustrate the invention, field operation of an in situ combustion process in the tar sand in the Bellamy,

Missouri, area indicated that the B.t.u. requirements for an improved process for recovering upgraded hydrocarmaintaining sustained combustion were in the order of 25,000 to 40,000 B.t.u. per cu. ft. of rock. If the hydrogenation of the carbonaceous material in, a cubic foot-of rock or sand releases suflicient energy to maintain a desirable hydrogenation temperature such as at least about 900-1,000 F., the injection of hydrogen into the hot stratum can be continued indefinitely and the hot reaction zone moves thru the stratum in a similar manner to the The hydrogen may be injected kca1./mol cal/gm. Btu/lb.

Methane .Q; 290 1, 030 1, 855 Propane 70 248 450 Assumingan equivalence between bitumens (semi-solid to solid hydrocarbons) .and n-eicosane, and using the figures of 4 to 12 pounds bitumen per cubic foot of sand, the ranges of heats that are released by hydrogenation are as follows:

B.t.u. re1eased per cu. ft. rock on hydrogenation of Bitumen content (lbs/cu. it.) bitumens to Methane Propane These rough calculations indicate that a sand of high bitumen content on complete gasification to methane by hydrogenation would release the minimum heat required to maintain an operative temperature in the range of 900 to l- 00 F or more.

' In order to facilitate the hydrogenation in the hot zone and render hydrogenation more effective and more rapid at lower temperatures such as down to 750 or 800 F .,hy drogenation catalysts may be injected in vapor form with the hydrogen. The carbonyls of the hydrogenating metals copper, vanadium, columbium, tantalum, chromium, molybdenum, tungsten, uranium, manganese, iron, cobalt, nickel, platinum, palladium, rhodium and ruthenium may be injected in vapor form with the hydrogen to increase ing metals in the form of metal compounds such as metal carbonates before the in situ combustion process is initiated by injecting aqueous solutions of these compounds and drying the stratum by injecting air into same. When the temperature of the stratum is raised during combustion and/ or hydrogenation, the metal compounds are converted to the metal oxides and at least partially to the metals which have strong catalytic activity on the hydrogenation reaction. I

In strata in which the hydrogenation reaction develops insufficient heat to continue the hydrogenation at temperatures which maintain reasonable rates of hydrogenato solid hydrocarbons which are fluidized by the in situ combustion process and a portion of which, in heavy viscous form, is driven into the stratum by direct air injection thru the ignition borehole where it becomes more viscous in the cooler stratum remote from the ignition borehole and congeal therein thereby plugging the stratum and cutting off the movement of air to the combustion front. In such a process,'the injection of air and the in situ combustion are continued only until the injection rate With a given pressure appreciably diminishes or the injection pressure rises appreciably and plugging becomes imminent. At this time, injection of air is terminated and the injection of hydrogen with or without vaporized catalyst is injected through the offset well(s) so as to drive heavy hydrocarbons. not only hydrogenates the heavy liquid hydrocarbons tion, the injection of hydrogen is terminated when an appreciable concentration of hydrogen appears in the produced gases recovered from the production well(s) and then the injection of air or other combustion-supporting gas is resumed so as to re-establish in situ combustion and again build up a substantial heat reservoir in the carbonaceous stratum. for another hydrogenation step inthe cycle. i

The invention is particularly advantageous when producing tar sands and other strata which contain semi-solid the viscous liquid hydrocarbon material back into the hot combustion area in admixture with the injected hydrogen Where the temperature is suificient to hydrogenate these Continued injection of hydrogen driven back into the hot zone and makes them readily flowable into the ignition well, but also hydrogenates other hydrocarbon material left in the hot combustion zone at the time the injection of air was terminated, In this manner hydrocarbons produced during the in situ combustion are recovered through the offset well(s) and hydrocarbons hydrogenated and produced during the hydrogenation phase of the process are recovered through the ignition well;

It is also feasible, and in some cases preferred, to in ject the hydrogen thru the ignition well after termination of the injection of air. In this manner hot hydrogenated light hydrocarbons pass thru the stratum containing the heavy viscous hydrocarbon material flushed thereto by the in situ combustion process and raise the temperature thereof so as to render same less viscous and flush these hydrocarbons to the offset production well(s). Injection of hydrogen is continued as long as the temperature in the hot zone remains sufficient to eifect hydrogenation at a reasonable rate and until hydrogen appears in a substantial concentration in the produced gases. When such occurs, injection of hydrogen is terminated and air injection is resumed and continued until plugging becomes imminent or at least until the effective permeability of the stratum is substantially reduced due to the driving of fluidized heavy hydrocarbons into the stratum beyond the combustion front, after which, the injection of air is again terminated and injection of hydrogen, either thru the ignition well or thru the offset well(s) is again resumed. In this manner, alternate in situ combustion and hydrogenation in separate steps are effected until the stratum is substantially completely produced.

The process of the invention involving both in situ combustion and hydrogenation also effects substantial hydrocracking which both cracks and hydrogenates hydrocarbons present in a siliceous rock or sand thereby improving (reducing) the viscosity substantially more than is effected by hydrogenation 0r cracking, alone.

It is,of course, to be understoodthat high pressures up to 2,000 psi. or more are advantageous in effecting the hydrogenation step. Since fairly high injection pressures are required to force the gases thru the stratum between the injection and production boreholes, the matter of pressure in the hydrogenation zone offers no problem in this process. In some strata, the temperature effected by in situ combustion is as high as 1400-1500 F. in many instances, but is usually abowe 1000 F. Hence, by establishing in situ combustion and maintaining this phase of the process for an appreciable period of time so as to movethe combustion zone several feet thru the stratum a substantial heat reservoir is created at ample temperature for the hydrogenation phase of the process.

Oertain modifications of the invention will become apparent to those skilled in the ant and the illustrative details disclosed are not to be construed as imposing unnecessary limitations on the invention.

I claim:

1. A process for hydrogenating and producing the hydrogenated hydrocarbons from a permeable hydrocarbonbearing stratum which comprises igniting hydrocarbons in said stratum along the wall of an ignition Well therein; advancing the resulting combustion zone radially into said stnatum toward an offset well therein by passing combustion-supporting gas thereto so as to establish an expanded combustion zone at a temperature of at least about 1000 F.; terminating injection of said combustion supporting gas; thereafter injecting H -containing gas into said combustionzone while at said temperature thru one of said wells so as to hydrogenate hydrocarbons therein and move a hydrogenating zone toward said offset well; terminating injection of Li -containing gas when the temperature in the hot reaction zone drops below about 800 F.; injecting combustion-supporting gas into the hot reaction zone to burn hydrocarbons therein, thereby advancing the combustion zone farther into said stratum and raising the temperature of said zone to at least 1200 F.; while at last said temperature, terminating injection of combustiomsupporti-ng gas into said zone and again injecting gas comprising free H so as to again hydrogenate hydrocarbons therein; and recovering hydrocarbons produced by both the combustion and the hydrogenation thru one of said wells.

2. The process of claim 1 wherein a carbonyl of a hydrogenating metal is injected in admixture with said H 3. The process of claim 2 wherein said metal is nickel.

4. The process of claim 2 wherein said metal is copper.

5. In a process for producing hydrocarbons in a permeable carbonaceous stratum containing semi-solid to solid hydrocarbons comprising igniting and burning carbonaceous material around an ignition Well therein by heating same to ignition temperature and injecting combustion-supporting gas thru said ignitionwell into said stratum, and recovering the produced fluids thru at least one oiiset well in said stratum, wherein a temperature of at least 1000 F. is established in the combustion zone and a substantial portion of said semi-solid to solid hydrocarbons is fluidized and driven into the cooler stratum away from said ignition well, thereby plugging said stratum and cutting off flow of said gas to the combnstion zone, the improvement comprising terminating said gas injection when said plugging is about to occur and injecting H -containing gas thru said at least one oifset well to the combustion zone so as to flush said fluidized hydrocarbons back into said zone in admixture with hydrogen and hydrogenate a substantial portion of said hydrocarbons in said zone; continuing the injection of H until the concentration of H in the produced gases indicates a low rate of hydrogenation; then terminating H injection and resuming injection of combustion supporting gas thru said ignition well; and recovering pro duced gases, including hydrogenated hydrocarbons, during the hydrogenation step thru said ignition well.

6. A process for producing hydrocarbons from a permeable carbonaceous stratum which contains semi-solid to solid hydrocarbons which become highly viscous liquid hydrocarbons during in situ combustion of said stratum, which comprises establishing combustion in said stratum around an ignition well therein; advancing the resulting combustion zone thru said stratum by injecting combustion-supporting gas thereto thru at least one offset well therein so as to establish a substantial heated zone at a temperature of at least 1000 F terminating the injection of said combustion-supporting gas; thereafter, while at said temperature, contacting the hot hydrocarbon material in said zone with H so as to hydrogenate a substantial portion thereof by injecting Pi -containing gas thru said ignition well into said stratum whereby the heated zone is advanced farther into said stratum; recovering produced fluids thr-u said ignition well during the combustion step and thru said offset well during the hydrogenation step; and terminating injection of H when the concentration of H in the produced fluids indicates a low rate of hydrogenation and resuming the injection of combustion-supporting gas.

7. The process of claim 6 wherein a carbonyl of a hydrogenating metal is injected in admixture with said H 8. The process of claim 7 wherein said metal is nickel.

9. The process of claim 7 wherein said metal is copper.

10. A process for hydrogenating and producing the hydrogenated hydrocarbons from a permeable hydrocarbon-bearing stratum which comprises igniting hydrocarbons in said stratum along the wall of an ignition well therein; advancing the resulting combustion zone radially into said stratum toward an offset well therein by passing combustion-supporting gas thereto thru said ignition Well so as to establish an expanded combustion zone at a temperature of at least 21000 F. and produce hydrocarbons thru said offset well; terminating injection of said combustion-supporting gas; thereafter injecting H -containing gas into said combustion Zone while at said temperature thru said offset well so as to drive fluid hydro- References Cited in the file of this patent UNITED STATES PATENTS 2,595,979 Pevere et al May 6, 1952 2,756,194 Mayland July 24, 1956 2,788,071 Pelzer Apr. 9, 1957 2,857,002 Pevere et al. Oct. 21, 1958 2,862,557 Baron van Utenhove et al Dec. 2, 1958 2,897,135 Doumani July 28, 1959 3,051,235 Banks Aug. 28, 1962 

1. A PROCESS FOR HYDROGENATING AND PRODUCING THE HYDROGENATED HYDROCARBONS FROM A PERMEABLE HYDROCARBONBEARING STRATUM WHICH COMPRISES IGNITING HYDROCARBONS IN SAID STRATUM ALONG THE WALL OF AN IGNITION WELL THEREIN; ADVANCING THE RESULTING COMBUSTION ZONE RRADIALLY INTO SAID STRATUM TOWARD AN OFFSET WELL THEREIN BY PASSING COMBUSTION-SUPPORTING GAS THERETO SO AS TO ESTABLISH AN EXPANDED COMBUSTION ZONE AT A TEMPERATURE OF AT LEAST ABOUT 1000*F.; TERMINATING INJECTION OF SAID COMBUSTIONSUPPORTING GAS; THEREAFTER INJECTING H2-CONTAINING GAS INTO SAID COMBUSTION ZONE WHILE AT SAID TEMPERATURE THRU ONE OF SAID WELLS SO AS TO HYDROGENATE HYDROCARBONS THEREIN AND MOVE A HYDROGENATING ZONE TOWARD SAID OFFSET WELL; TERMINATING INNJECTION OF H2-CONTAINING GAS WHEN THE TEMPERATURE IN THE HOT REACTION ZONE DROPS BELOW ABOUT 800*F.; INNJECTING COMBUSTION-SUPPORTING GAS INTO THE HOT REACTION ZONE TO BURN HYDROCARBONS THEREIN, THEREBY ADVANCING THE COMBUSTION ZONE FARTHER INTO SAID STRATUM AND RAISING THE TEMPERATURE OF SAID ZONE TO AT LEAST 1200* F.; WHILE AT LAST SAID TEMPERATURE, TERMINATING INJECTION OF COMBUSTION-SUPPORTING GAS INTO SAID ZONE AND AGAIN INJECTING GAS COMPRISING FREE H2 SO AS TO AGAIN HYDROGENATE HYDROCARBONS THEREIN; AND RECOVERING HYDROCARBONS PRODUCED BY BOTH THE COMBUSTION AND THE HYDROGENATION THRU ONE OF SAID WELLS. 